Nozzle comprising axial extension for a combustion chamber of an engine

ABSTRACT

The present invention relates to a nozzle for a combustion chamber ( 3 ) of an engine (T) for providing a fuel-air mixture at a nozzle exit opening of the nozzle ( 2 ). According to the invention, an extension ( 5 ) for guiding the fuel-air mixture extending in the axial direction with respect to a nozzle longitudinal axis (DM) is provided at an air guide element ( 271   b ) of a radially outwardly located air channel ( 27   b ) of the nozzle ( 2 ).

The invention relates to a nozzle for a combustion chamber of an enginefor providing a fuel-air mixture at a nozzle exit opening of the nozzle.

An (injection) nozzle for a combustion chamber of an engine, inparticular for an annular chamber of a gas turbine engine, comprises anozzle main body that has a nozzle exit opening and that, in addition toa fuel guiding channel for conveying fuel to the nozzle exit opening,has multiple (at least two) air guiding channels for conveying airintermixed with fuel to the nozzle exit opening. A nozzle usually alsoserves for swirling the supplied air, which, intermixed which thesupplied fuel, is subsequently conveyed into the combustion chamber atthe nozzle exit opening of the nozzle. For example, multiple nozzles maybe grouped together in a nozzle assembly group that comprises multiplenozzles arranged next to each other, usually along a circular line, forintroducing fuel into the combustion chamber.

In nozzles with multiple air guiding channels and at least one fuelguiding channel as they are known from the state of the art, for examplefrom U.S. Pat. No. 9,423,137 B2, it is provided that a first air channelextends along a nozzle longitudinal axis of the nozzle main body and afuel guiding channel is positioned radially further outwards than thefirst air channel with respect to the nozzle longitudinal axis. In thatcase, it is additionally provided that at least one further air channelis positioned radially further outwards than the fuel guiding channelwith respect to the nozzle longitudinal axis. Here, one end of the fuelguiding channel at which the fuel form the fuel guiding channel flowsout in the direction of the air from the first air guiding channel istypically located—with respect to the nozzle longitudinal axis and inthe direction of the nozzle exit opening—in front of the end of thesecond air channel from which the air then flows out in the direction ofa mixture of air from the first air channel and fuel from the fuelguiding channel. What is further provided in the state of the art andfor example also provided in U.S. Pat. No. 9,423,137 B2 is to providesuch a nozzle with a third air channel, with its end, which may also bedisplaced radially outwards, following the end of the second air channelin the axial direction.

The nozzle is positioned at the combustion chamber via a burner sealthat seals the nozzle towards the combustion space of the combustionchamber. Here, the burner seal is usually floatingly mounted at a headplate of the combustion chamber to compensate for radial and axialmovements between the nozzle and the combustion chamber and to ensure areliable sealing effect in different operating states.

For guiding the fuel-air mixture provided by the nozzle, the burner sealoften has a flow guiding element at the combustion space side. However,due to the axial displaceability of the nozzle relative to the burnerseal and its flow guiding element, here the aerodynamic conditions varydepending on the operational state of the engine. Also, a radialdistance between the nozzle and the burner seal, which has to beprovided due to the construction, renders it more difficult to achievean exactly predefined guidance of the fuel-air mixture via the flowguiding element of the burner seal. Both above-mentioned aspectsinfluence the development of undesired soot emissions.

Against this background, there is the objective to provide a combustionchamber assembly group that is improved in this regard and thatcomprises a nozzle for providing a fuel-air mixture.

This objective is achieved through a nozzle of claim 1.

What is proposed according to the invention is a nozzle for a combustionchamber of an engine for providing a fuel-air mixture at a nozzle exitopening of the nozzle, wherein the nozzle comprises the nozzle main bodythat comprises the nozzle exit opening and that extends along a nozzlelongitudinal axis. Here, the nozzle main body further comprises at leastthe following:

-   -   at least one first, inner air channel for conveying air to the        nozzle exit opening, extending along the nozzle longitudinal        axis,    -   at least one fuel guiding channel for conveying fuel to the        nozzle exit opening that is positioned radially further outwards        as compared to the first air channel with respect to the nozzle        longitudinal axis, and    -   at least one further air channel positioned radially further        outwards compared to the fuel guiding channel with respect to        the nozzle longitudinal axis, wherein an air guide element for        guiding air that flows from the at least one further air channel        is provided at an end of this at least one further air channel        that is positioned in the area of the nozzle exit opening.

Now an extension for guiding the fuel-air mixture extending in the axialdirection with respect to the nozzle longitudinal axis is provided atthe air guide element of the at least one further air channel. Here, theaxial direction along which the extension extends is oriented towards acombustion space of the combustion chamber when the combustion chamberassembly group comprising the nozzle is arranged at a combustion chamberaccording to the intended use. Thus, the axial extension is locatedinside the combustion space and extends in the flow direction of thefuel-air mixture to be provided if the nozzle is arranged at thecombustion chamber according to the intended use.

In a nozzle according to the invention, it is thus provided that thenozzle main body is formed with an extension for guiding the fuel-airmixture that is provided at the nozzle exit opening in the area of theair guide element of the at least one further (in the case of multipleair guiding channels of the radially outermost) air channel. Thus, theaxial extension is configured and provided for guiding the createdmixture of the fuel from the fuel guiding channel and the air from thefirst, inner air channel as well as the at least one further airchannel. While thus the air guide element of the at least one furtherair channel is configured and provided for guiding air from the at leastone further air channel, in particular for deflecting the flowing andusually swirled air with a radially inwardly oriented directionalcomponent, the axial extension is configured and provided for guidingthe created fuel-air mixture. In this way, a mixture guidance isintegrated in the nozzle, whereby any flow elements at thecombustion-space side can be omitted at a burner seal via which thenozzle is positioned at the combustion chamber. In this way, the burnerseal can be limited to its sealing function, and can be embodied withoutaerodynamic elements that influence the flow. By integrating the mixtureguidance at the nozzle itself, any axial displacement of the nozzle andthe burner seal relative to each other occurring as a result ofoperation does not have any negative influences on the guidance of thefuel-air mixture.

In an exemplary embodiment, the extension is formed in a tubular manner.In that case, the extension may for example be embodied in the kind of atube piece at the combustion-space side end of the nozzle main body. Inparticular, the extension can be formed or molded at the nozzle mainbody as a tubular end piece.

In an exemplary embodiment it is provided that the extension extends inthe axial direction with a length that is less than 3.5 times a heightof the at least one further air channel and/or that is less than 3.5.times a height of a swirling element provided in the at least onefurther air channel. In this embodiment variant, given a height H of theat least one further air channel or of the swirling element, thefollowing thus applies to a length l₅ with which the extension extendsin the axial direction: l₅≤3.5 H. A corresponding geometric correlationbetween the length of the axial extension and the height of the at leastone further air channel and/or of a swirling element provided in thisair channel has proven to be advantageous for influencing the flow.

Alternatively or additionally, it can be provided that the air guideelement of the at least one further air channel has a section (which ishollow and is passed by air from the air channel during operation of theengine) at which an inner diameter defined by the air guide element andthus the cross-sectional surface of the nozzle exit opening which ispassable by a flow is minimal, and the extension—measured from a firstreference point at this section and at the location of the minimal innerdiameter—extends in the axial direction up to a second reference pointthat is located at a certain distance from the first reference point.Here, it may for example be provided that the distance between the firstreference point and the second reference point that is measured alongthe nozzle longitudinal axis

-   (a) is at least as great as a height of the at least one further air    channel and/or a height of a swirling element that is provided    inside the at least one further air channel, and-   (b) maximally corresponds to 3.5 times this height.

As for the distance I between the first reference point at the minimalinner diameter of the air guide element and the second reference pointthat is located downstream thereto, the following correspondinglyapplies for a height H of the at least one further air channel or of theswirling element provided therein: H≤I≤3.5 H.

In one embodiment variant, a radially outwardly located lateral surfaceof the extension connects to a radially outwardly located lateralsurface of the air guide element. This in particular includes that theair guide element and the extension have substantially or exactly thesame outer diameter. Thus, through this extension, a maximal outerdiameter of the nozzle is enlarged at its end that projects into thecombustion space in the mounted state according to the intended use.

Alternatively or additionally, an inner lateral surface of the extensionconnects to an inner lateral surface of the air guide element of the atleast one further air channel in the axial direction. An inner lateralsurface of the air guide element thus transitions into the inner lateralsurface of the extension without any steps or without any projection orrecess, for example. In this way, the lateral surfaces of the extensionand of the air guide element continuously transition into each other insuch an embodiment variant.

In one embodiment variant, the extension has at least two sectionssucceeding each other in the axial direction and having different innerdiameters. This for example includes that a first section of theextension with an inner diameter which remains constant in the axialdirection (along the nozzle longitudinal axis) is provided upstream of asecond section, with the latter having a different inner diameter thatbe increasing up to the end of the extension, if necessary. Here, acontinuous widening of the opening that is passed by the flow can beprovided in the second section.

In a further development, a length of a second (end-side) sectionmeasured in the axial direction and having a larger and/or increasinginner diameter in the axial direction is considerably smaller than acorresponding (axial) length of the first section. For example, thelength of the second downstream, shorter section represents only afraction of the length of the first section.

Alternatively or additionally, an inner diameter (of the nozzle exitopening) can increase continuously or at least with one step in theaxial direction at least at one section of the extension. Thus, thisvariant in particular includes the previously described variant in whichtwo sections with different inner diameters are provided. But this alsoincludes variants in which not only a section of the extension, but theextension itself has an inner diameter that increases continuously in adiffuser-like manner. In particular, it can be provided that the atleast one section of the extension or the extension itself has an innerlateral surface that extends in a manner pointing radially outwards withrespect to the nozzle longitudinal axis and/or that is concavely curved.For example, in one exemplary embodiment, the inner lateral surface ofthe extension defines a (nozzle exit) opening for the fuel-air mixturewidening in the shape of a truncated cone. With regard to the flowguidance, where appropriate, an additionally provided widening of the(nozzle exit) opening defined by the extension can be provided, inparticular at an end of the extension that is located in the axialdirection.

In contrast to the previously explained embodiment variants, in oneembodiment variant it can also be provided that the extension has aconstant inner diameter in the axial direction.

A further aspect of the suggested solution relates to the provision of acombustion chamber assembly group, with a burner seal that comprises abearing section having a passage opening and extending along the nozzlelongitudinal axis, and with a nozzle that is positioned inside thepassage opening of the bearing section. In that case, the nozzle alsohere has an extension for guiding the fuel-air mixture extending in theaxial direction.

Here, it is provided in one embodiment variant that the extension of thenozzle projects in the axial direction (which is oriented to acombustion space of the combustion chamber if the combustion chamberassembly group is arranged at a combustion chamber according to theintended use) beyond the bearing section. Thus, the guidance of thefuel-air mixture that is provided at the nozzle exit opening in thedirection of the combustion space is realized exclusively by means ofthe nozzle and its axial extension.

In particular against this background, it can be provided in oneembodiment variant that the burner seal is formed without flow guidingelements (at the combustion-space side). The burner seal is thus limitedto its sealing function and is not designed for an aerodynamic function.In that case, the function of the flow guidance of the fuel-air mixtureis taken over exclusively or at least predominantly by the nozzle withits axial extension.

Moreover, an engine with at least one nozzle according to the inventionor a combustion chamber assembly group according to the invention isalso provided within the scope of the solution according to theinvention.

The attached Figures illustrate possible embodiment variants of thesuggested solution by way of example.

Herein:

FIGS. 1 to 7 show, respectively in sections and in cross-sectional view,different embodiment variants of a nozzle according to the inventionwith an axial extension in the area of a nozzle exit opening;

FIG. 8A shows an engine in which a combustion chamber with a nozzleaccording to one of the embodiment variants of FIGS. 1 to 7 is used;

FIG. 8B shows, in sections and an enlarged scale, the combustion chamberof the engine of FIG. 8A;

FIG. 8C shows, in a cross-sectional view, the basic structure of anozzle according to the state of the art and the surrounding componentsof the engine in the installed state of the nozzle;

FIG. 8D shows a back view of a nozzle exit opening, also illustratingswirling elements that are provided in radially outwardly located airguiding channels of the nozzle.

FIG. 8A schematically illustrates, in a sectional view, a (turbofan)engine T in which the individual engine components are arranged insuccession along a rotational axis or central axis M and the engine T isembodied as a turbofan engine. By means of a fan F, air is suctioned inalong an entry direction at an inlet or an intake E of the engine T.This fan F, which is arranged inside a fan housing FC, is driven via arotor shaft S that is set into rotation by a turbine TT of the engine T.Here, the turbine TT connects to a compressor V, which for example has alow-pressure compressor 11 and a high-pressure compressor 12, and wherenecessary also a medium-pressure compressor. The fan F supplies air tothe compressor V in a primary air flow F1, on the one hand, and, on theother, to a secondary flow channel or bypass channel B in a secondaryair flow F2 for creating a thrust. Here, the bypass channel B extendsabout a core engine that comprises the compressor V and the turbine TT,and also comprises a primary flow channel for the air that is suppliedto the core engine by the fan F.

The air that is conveyed via the compressor V into the primary flowchannel is transported into the combustion chamber section BKA of thecore engine where the driving power for driving the turbine TT isgenerated. For this purpose, the turbine TT has a high-pressure turbine13, a medium-pressure turbine 14, and a low-pressure turbine 15. Theturbine TT drives the rotor shaft S and thus the fan F by means of theenergy that is released during combustion in order to generate thenecessary thrust by means of the air that is conveyed into the bypasschannel B. The air from the bypass channel B as well as the exhaustgases from the primary flow channel of the core engine are dischargedvia an outlet A at the end of the engine T. Here, the outlet A usuallyhas a thrust nozzle with a centrally arranged outlet cone C.

FIG. 8B shows a longitudinal section through the combustion chambersection BKA of the engine T. Here, in particular an (annular) combustionchamber 3 of the engine T can be seen. A nozzle assembly group isprovided for injecting fuel or an air-fuel-mixture into a combustionspace 30 of the combustion chamber 3. It comprises a combustion chamberring R along which multiple (fuel/injection) nozzles 2 are arrangedalong a circular line about the central axis M. Here, the nozzle exitopenings of the respective nozzles 2 that are positioned inside thecombustion chamber 3 are provided at the combustion chamber ring R.Here, each nozzle 2 comprises a flange by means of which a nozzle 2 isscrewed to an outer housing G of the combustion chamber 3.

FIG. 8C now shows a cross-sectional view of the basic structure of anozzle 2 as well as the surrounding components of the engine T in theinstalled state of the nozzle 2. Here, the nozzle 2 is part of acombustion chamber system of the engine T. The nozzle 2 is locateddownstream of a diffuser DF and during mounting is inserted through anaccess hole L through a combustion chamber head 31, through a heatshield 300 and a head plate 310 of the combustion chamber 3 up to thecombustion space 30 of the combustion chamber 3, so that a nozzle exitopening formed at a nozzle main body 20 reaches all the way to thecombustion space 30. The nozzle 2 further comprises a nozzle neck 21which substantially extends radially with respect to the central axis Mand inside of which a fuel supply 210 conveying fuel to the nozzle mainbody 20 is accommodated. Further formed at the nozzle main body 20 are afuel chamber 22, fuel passages 220, heat shields 23 as well as airchambers for insulation 23 a and 23 b.

In addition, the nozzle main body 20 forms a (first) inner air channel26 extending centrally along a nozzle longitudinal axis DM and,positioned radially further outside with respect to the same, a (secondand third) outer air guiding channel 27 a and 27 b. These air guidingchannels 26, 27 a and 27 b extend in the direction of the nozzle exitopening of the nozzle 2.

Further, also at least one fuel guiding channel 26 is formed at thenozzle main body 20. This fuel guiding channel 25 is located between thefirst inner air channel 26 and the second outer air channel 27 a. Theend of the fuel guiding channel 25, via which fuel flows out in thedirection of the air from the first inner air channel 26 duringoperation of the nozzle 2, is located—with respect to the nozzlelongitudinal axis DM and in the direction of the nozzle exit opening—infront of the end of the second air channel 27 a from which air from thesecond, outer air channel 27 a flows out in the direction of a mixtureof air from the first, inner air channel 26 and fuel from the fuelguiding channel 25.

Swirling elements 270 a, 270 b for swirling the air supplied through theair guiding channels 27 a and 27 b are provided in the outer air guidingchannels 27 a and 27 b. Further, the nozzle main body 20 also comprisesan outer, radially inwardly oriented air guide element 271 b at the endof the third outer air channel 27 b. In the nozzle 2, which may e.g. bea pressure-assisted injection nozzle, the ends of the second and thirdradially outwardly located air guiding channels 27 a and 27 bfollow—with respect to the nozzle longitudinal axis DM and in thedirection of the nozzle exit opening—the end of the fuel guiding channel25 from which fuel is supplied to the air from the first inner centrallyextending air channel 26 during operation of the engine T, according toFIG. 8C. Air that is swirled by means of the swirling elements 270 a,270 b is transported to the nozzle exit opening form these second andthird air guiding channels 27 a and 27 b. As is shown in the back viewof FIG. 8D with a view of the nozzle exit opening along the nozzlelongitudinal axis DM, these swirling elements 270 a, 270 b are arrangedinside the respective air channel 27 a, 27 b in a circumferentiallydistributed manner.

A sealing element 28 is also provided at the nozzle main body 20 at itscircumference for sealing the nozzle 2 towards the combustion space 30.This sealing element 28 forms a counter-piece to a burner seal 4. Thisburner seal 4 is floatingly mounted between the heat shield 300 and thehead plate 310 to compensate for radial and axial movements between thenozzle 2 and the combustion chamber 3 and to ensure reliable sealing indifferent operational states.

The burner seal 4 usually has a flow guiding element 40 towards thecombustion space 30. In connection with the third outer air channel 27 bat the nozzle 2, this flow guiding element 40 ensures a desired flowguidance of the fuel-air mixture that results from the nozzle 2, moreprecisely the swirled air from the air guiding channels 26, 27 a and 27b, as well as the fuel guiding channel 25.

In an embodiment of a burner assembly group according to FIG. 8C as itis known in the state of the art, it is disadvantageous that therelative position of the burner seal 4, and in particular its flowguiding element 40, to the nozzle 2 can change during operation of theengine T in particular due to thermal extensions. Thus, an aerodynamiceffect of the burner seal 4, and in particular the guidance of thefuel-air mixture across the flow guiding element 40, varies depending onthe operational conditions.

This problem is remedied by the suggested solution, for which differentembodiment variants are shown in the FIGS. 1 to 7.

Here, it is respectively provided that an extension 5 is provided at theair guide element 271 b of the outermost, third air channel 27 b,extending in the axial direction in order to guide the resultingfuel-air mixture in the direction of the combustion space 30. Thisextension 5, which may for example be formed or molded integrally at thenozzle main body 20, respectively projects beyond a bearing section 41of the burner seal 4 at the combustion chamber side. The passage openingthrough which the nozzle 2 is positioned at the burner seal 4 isprovided in this bearing section 41. By thus guiding the fuel-airmixture through the nozzle-side extension 5 in the direction of thecombustion space 30 at the nozzle exit opening, the burner seal 4 doesno longer take over an aerodynamic function. The burner seal 4 now onlyserves the purpose of sealing, and is correspondingly formed without aflow guiding element 40.

In particular in the nozzle 2 of FIG. 1 it is provided that theextension 5 of the shown embodiment variants that connects to the airguide element 271 b has an outer diameter D2 that substantiallycorresponds to the outer diameter of the air guide element 271 b andthus the nozzle 2 in the area of the burner seal 4. The extension 5 ofthe respective nozzle 2 is further designed in a tubular manner, and hasan axial length l₅ that is less than 3.5. times a height H of theswirling element 270 b provided in the third air channel 27 b.

Further, the axial expansion of extension 5 is respectively dimensionedin such a manner that other geometric conditions having proven to beadvantageous are met. Thus, for guiding the air flowing out of the airchannel 27 b radially inwards, the air guide element 271 b of the thirdair channel 27 b defines an area with a minimal inner diameter D1 andthus a minimal cross-sectional surface of the nozzle exit openingthrough which the flow passes. A distance I of a reference point E1 atthe location of this minimal inner diameter D1 to a further referencepoint E2 located in the axial direction and marking the end of theextension 5 is now dimensioned such that the following applies:H≤I≤3.5≤H.

In particular the extension 5 of the nozzle 2 shown in FIG. 1 has twosuccessive sections 50 and 51 with different inner diameters. Thus,initially a first section 50 with an inner diameter which remainsconstant along the nozzle longitudinal axis DM connects to the air guideelement 271 b. If is followed in the direction of the combustion space30 by a considerably shorter, second section 51, where the innerdiameter increases and accordingly the extension 5 widens.

While in the embodiment variant of FIG. 1 the extension 5 forms a ledge,and thus a recess at which the inner diameter is enlarged comparativelyabruptly, in the transition from the air guide element 271 b of theradially outermost, third air channel 27 b, the embodiment variant ofFIG. 2 provides an extension 5 with a smoother transition between aninner lateral surface of the air guide element 271 b and an innerlateral surface of the extension 5. Here, the extension 5 is furthercontinuously enlarged in a diffuser-like manner, so that an innerdiameter of the extension 5 is continuously enlarged in the axialdirection, and the inner lateral surface of the extension 5 extendsradially outwards with respect to the nozzle longitudinal axis DM.

In contrast, in the variants of FIGS. 3 and 4, the transition betweenthe air guide element 271 b and the extension 5 is realized through aledge. However, in contrast to the variants of FIGS. 1 and 2, here thedownstream (end-side) section 51 is embodied so as to taper off towardsthe trailing edge.

In the variant shown in FIG. 5, the extension 5 has a slightly concaveinner curvature for a smoother transition between the air guide element271 b and the extension 5. Here, the lateral surfaces of the air guideelement 271 b and the extension 5 transition into each other withoutsteps. Thus, a flow is guided along the air guide element 271 b and theextension 5 along their inner lateral surface, which transitions withoutany edges. Further, a slightly convex inner curvature is provided at thedownstream distal end of the extension 5.

In the embodiment variant of FIG. 6, the extension 5 is also designed insuch a manner that the lateral surfaces of the air guide element 271 band the extension 5 transition into each other without any steps at atransition 52, and the extension 5 thus directly connects to the airguide element 271 b of the radially outermost, third air channel 27 b.Also in this case, the extension 5 is embodied in such a manner that theextension 5 widens continuously in the axial direction along the nozzlelongitudinal axis DM all the way to a tapering trailing edge. Here, theinner lateral surface of the extension 5 is slightly concavely curved.

In contrast to the embodiment variant of FIG. 6, the embodiment variantof FIG. 7 provides a continuous, diffuser-like widening of the extension5 directly connecting to the air guide element 271 b through an innerlateral surface that extends in a linear manner and is oriented radiallyoutwards at a constant angle to the nozzle longitudinal axis DM.

In the shown embodiment variants of FIGS. 1 to 7, the nozzle 2 isrespectively axially extended at a radially outermost third air channel27 b downstream of an air guide element 271 b. The axial extension 5provided for this purpose is respectively formed in a tubular manner andhas the same outer diameter D2 as the nozzle 2 in the area of the burnerseal 4. Here, the inner contour of the extension 5 is respectivelychosen in such a manner that a widening of the extension 5 occurs alongthe nozzle longitudinal axis DM in the direction of the combustion space30 at least in one section. Through the embodiment of the extension 5 atthe nozzle 2 at which the resulting fuel-air mixture is guided in thedirection of the combustion space 30, an admissible axialdisplaceability of the burner seal 4 and the nozzle 2 relative to eachother does not influence the guidance of the fuel-air mixture. This isin particular advantageous when it comes to avoiding interfering sootemissions. Further, here the burner seal 4 seal only has to beconfigured and embodied for ensuring the sealing effect. The integrationof a flow guiding element 40 at the burner device 4 may be omitted.

PARTS LIST

-   11 low-pressure compressor-   12 high-pressure compressor-   13 high-pressure turbine-   14 medium-pressure turbine-   15 low-pressure turbine-   2 nozzle-   20 nozzle main body-   21 neck-   210 fuel supply-   22 fuel chamber-   220 fuel passage-   23 heat shield-   24 a, 24 b air chamber-   25 fuel guiding channel-   26 first air channel-   270 a, 270 b swirling element-   271 b air guide element-   27 a second air channel-   27 b third air channel-   28 sealing element-   3 combustion chamber-   30 combustion space-   300 heat shield-   31 combustion chamber head-   310 head plate-   4 burner seal-   40 flow guiding element-   41 bearing section-   5 extension-   50, 51 section-   52 transition-   A outlet-   B bypass channel-   BKA combustion chamber section-   C outlet cone-   D1, D2 diameter-   DF diffuser-   DM nozzle longitudinal axis-   E inlet/intake-   E1, E2 reference point/end area-   F fan-   F1, F2 fluid flow-   FC fan housing-   G outer housing-   H height-   L access hole-   I distance-   l₅ length-   M central axis/rotational axis-   R combustion chamber ring-   S rotor shaft-   T (turbofan) engine-   TT turbine-   V compressor

1. Nozzle for a combustion chamber (3) of an engine (T) for providing afuel-air mixture at a nozzle exit opening of the nozzle (2), wherein thenozzle (2) comprises a nozzle main body (20) that comprises the nozzleexit opening and that extends along a nozzle longitudinal axis (DM), andthe nozzle main body (20) further comprises at least the following: atleast one first, inner air channel (26) for conveying air to the nozzleexit opening, extending along the nozzle longitudinal axis (DM), atleast one fuel guiding channel (25) for conveying fuel to the nozzleexit opening that is positioned radially further outside than the firstair channel (26) with respect to the nozzle longitudinal axis (DM), andat least one further air channel (27 b) that is positioned radiallyfurther outside than the fuel guiding channel (25) with respect to thenozzle longitudinal axis (DM), wherein an air guide element (271 b) forguiding air flowing from the at least one further air channel (27 b) isprovided at an end of this at least one further air channel (27 b) thatis positioned in the area of the nozzle exit opening, characterized inthat an extension (5) for guiding the fuel-air mixture is provided atthe air guide element (271 b) of the at least one further air channel(27 b), extending in the axial direction with respect to the nozzlelongitudinal axis (DM).
 2. Nozzle according to claim 1, characterized inthat the extension (5) is embodied in a tubular manner.
 3. Nozzleaccording to claim 1 or 2, characterized in that the extension (5)extends in the axial direction with a length (l₅) that is less than 3.5.times a height (H) of the at least one further air channel (27 b) and/orof a swirling element (270 b) that is provided in the at least onefurther air channel (27 b).
 4. Nozzle according to any of the claims 1to 3, characterized in that the air guide element (271 b) of the atleast one further air channel (27 b) has a section at which an innerdiameter (D1) of the nozzle exit opening defined by the air guideelement (271 b) is minimal, and the extension (5), as measured from afirst reference point (E1) at this section and the location of theminimal inner diameter (D1), extends in the axial direction all the wayto a second reference point (E2) that is located at a distance (I) fromthe first reference point (E1), which (a) is at least as large as aheight (H) of the at least one further air channel (27 b) and/or of aswirling element (270 b) that is provided inside the at least onefurther air channel (27 b), and (b) corresponds to maximally 3.5 timesthis height (H).
 5. Nozzle according to any of the preceding claims,characterized in that a radially outwardly located lateral surface ofthe extension (5) connects to a radially outwardly located lateralsurface of the air guide element (271 b).
 6. Nozzle according to claim5, characterized in that the air guide element (271 b) and the extension(5) have substantially or exactly the same outer diameter (D2). 7.Nozzle according to any of the preceding claims, characterized in thatan inner lateral surface of the extension (5) connects in the axialdirection to an inner lateral surface of the air guide element (271 b)of the at least one further air channel (27).
 8. Nozzle according to anyof the preceding claims, characterized in that the extension (5) has atleast two sections (50, 51) succeeding each other in the axial directionand having different inner diameters.
 9. Nozzle according to any of thepreceding claims, characterized in that an inner diameter is enlargedcontinuously or with at least one step in the axial direction at leastat a section of the extension (5).
 10. Nozzle according to claim 9,characterized in that the at least one section of the extension (5) hasan inner lateral surface that extends so as to be oriented radiallyoutwards with regard to the nozzle longitudinal axis (DM) and/or that isconcavely curved.
 11. Nozzle according to any of the claims 1 to 7,characterized in that the extension (5) has an inner diameter that isconstant in the axial direction.
 12. Nozzle according to any of thepreceding claims 1 to 10, characterized in that the extension (5) widensat least at one end that is located in the axial direction. 13.Combustion chamber assembly group, with a burner seal (4) that has abearing section (41) having a passage opening and extending along thenozzle longitudinal axis (DM), and a nozzle (2) according to any of theclaims 1 to 12 that is positioned in the passage opening of the bearingsection (41).
 14. Combustion chamber assembly group according to claim13, characterized in that the extension (5) of the nozzle (2) projectsbeyond the bearing section (41) in the axial direction.
 15. Combustionchamber assembly group according to claim 13 or 14, characterized inthat the burner seal (4) is formed without flow guiding elements (40).16. Engine with at least one nozzle according to any of the claims 1 to12 or a combustion chamber assembly group according to any of the claims13 to 15.